Corrugated hose assembly

ABSTRACT

According to the present invention, there is provided a hose assembly with an inner fluoropolymer layer having a smooth inner surface and an outer polyamide layer having an undulated surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.09/634,277, filed Aug. 9, 2000 now U.S. Pat. No. 6,641,884, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The subject invention relates to a hose construction. More specifically,the subject invention relates to a hose assembly having an innerfluoropolymer layer with a polyamide outer layer used in automotive,aeronautics and other environs for carrying fluids, such as fuels.

2. Description of Related Art

Hose assemblies for conveying fuels are well known in the art. Suchassemblies are exposed to a variety of fuel mixtures and fuel additivesin addition to extreme engine temperatures. Such hose assemblies must beresistive to chemicals, as well as heat resistant to degradation as aresult of chemical and heat exposure.

Fluoropolymer materials, such as polytetrafluoroethylene possess therequisite chemical and temperature resistant properties for most fuelhose applications. However, fluoropolymer materials exhibit relativelypoor tensile and hoop strengths. As a consequence, such fluorinatedmaterials are prone to kinking. Such kinking remains permanent andprovides a continual resistance to fluid flow through the hose assembly.Moreover, as a result of the fluorinated material low tensile strength,attachment of securing or coupling members to the hose assembly isunreliable.

Various approaches have been described for offering additional strengthto a fluoropolymer layer. One approach involves braiding fibers aboutthe inner fluorocarbon layer. The braided fibers offer additionalstrength for the fluorocarbon layer resulting in a hose assembly thatresists kinking. An example of such an approach is disclosed inco-pending U.S. Ser. No. 08/535,734, filed Jun. 11, 1990, and assignedto the assignee of the subject invention. A drawback of such braidingtechniques, however, is the extensive labor and time involved.

Additional examples for strengthening an inner fluorocarbon layer withan outer layer are shown in U.S. Pat. No. 2,991,808 to Sigmann, U.S.Pat. No. 4,104,095 to Shaw, and U.S. Pat. No. 4,800,109 to Washizo, allof which disclose the use of a polytetrafluoroethylene inner layersupported with an outer layer.

Alternatively, some patents in the prior art utilize both an outer layerand a braided layer for added strength as shown in U.S. Reissue No.35,527. However, there remains problems with the bending capabilities ofsuch tubing in conjunction with the outer layer.

Furthermore, some patents in the prior art utilize multi-layer hoseswith corrugated outer surfaces for added strength at the bending sites,as shown in the U.S. Pat. No. 5,305,799, to Holmgren. However, theseprocesses have not been utilized for hoses having an inner fluoropolymerlayer and an outer polyamide layer.

Additionally, some patents in the prior art utilize machines forcreating corrugation, as shown in the U.S. Pat. No. 3,864,446, toMaroschak. However, there remains problems in creating corrugationwithout having to corrugate the entire hose assembly.

It would therefore be useful to develop a hose which is resistant tokinking when being bent without adding extensive labor or time to themanufacturing process.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a hose assemblywith an inner fluoropolymer layer having a smooth inner surface and anouter polyamide layer having an undulated surface. A method is providedfor making a hose assembly by forming a smooth inner fluoropolymer layerwithout undulations and an outer polyamide layer having undulations.

DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated asthe same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a prospective view partially broken away and in cross sectionof the preferred embodiment of the subject invention;

FIG. 2 is a prospective view partially broken away and in cross sectionof an alternate embodiment of the subject invention;

FIG. 3 is a prospective view partially broken away and in cross sectionof an alternate embodiment of the subject invention;

FIG. 4 is a schematic view, of a fuel system showing three separateapplications of the subject invention.

DETAILED DESCRIPTION OF THE INVENTION

A hose assembly made in accordance with the present invention isgenerally shown at 10 and FIGS. 1, 2, and 3. The assembly 10 includes atubular inner layer 12, an outer layer 14 disposed about the inner layer12, an integral conductive strip 16 co-extensive with the length of theinner layer 12 coupling mechanism 18 (FIG. 4) adapted to engage the endof the hose assembly 10 and undulations or corrugations 42 on the outersurface of the outer layer 14.

The tubular inner layer 12, as best shown in FIGS. 1, 2, and 3, is madefrom a fluoropolymer material resistant to both chemical and heatdegradation, allowing a variety of fluids, particularly automotive fuelsand fuel additives, e.g., detergents, alcohols, etc., to pass throughthe inner layer 12 without corroding or degrading the inner layer 12.The inner layer 12 is preferably extruded using well-known melt or pasteextrusion techniques and has a wall thickness of between 0.001 and 0.120inches.

Although the inner layer 12 may be made of any number of fluoropolymermaterials, the inner layer 12 is ideally made from a polymer of thefollowing: polytetrafluoroethylene (PTFE), the homopolymer oftetrafluoroethylene sold under the trademark TEFLON by DuPont;perfluorinated ethylene-propylene (FEP), the copolymer oftetrafluoroethylene and hexafluoropropylene sold under the trademarkTEFLON FEP by DuPont; perfluoroalkoxy fluorocarbon resin (PFA), thecopolymer of tetrafluoroethylene-perfluorovinyl ethyl, sold under thetrademark TEFLON PFA by DuPont; or ethylene tetrafluoroethylene (ETFE),the copolymer of ethylene and tetrafluoroethylene sold under thetrademark TEFZEL by DuPont PVDF and THV. In addition to theaforementioned fluoropolymer materials, polychlorotrifluoroethylene, thehomopolymer of chlorotrifluoroethylene, andpolychlorotrifluoroethylene-ethylene, the copolymer ofchlorotrifluoroethylene and ethylene may also be used.

The outer layer 14, best shown in FIGS. 1, 2, and 3, is disposed aboutthe inner layer 12. The outer layer 14 is made up of polyamide materialfor increasing strength of the hose assembly 10. More specifically, theouter layer 14 allows the inner layer 12 to bend without kinking. Thatis, the outer layer 14 provides strength to the inner layer 12 uponbending. This is commonly referred to as hoop strength. Thus, bydisposing the outer layer 14 having undulations 42 about the inner layer12, the hoop strength of the inner layer 12 is increased. Further, theouter layer 14 adds to the working pressure of the hose. That is, theouter layer 14 provides strength to the inner layer 12 and allows theinner layer 12 to accommodate a fluid under pressure. Additionally, theouter layer 14 adds to the tensile strength of the hose assembly 10.When coupling members 18 (FIG. 6) are disposed at the ends of the hoseassembly 10, as described below, the outer layer 14 increases thetensile strength of the hose assembly 10 sufficient to fixedly connectthe coupling member 18 (FIG. 4) to the hose assembly 10. By disposingthe outer layer 14 having undulations 42 about the inner layer 12, thebend radius of the hose is increased.

Although the outer layer 14 may be made of any number of polyamidematerials, preferably the outer layer 14 is made from a polyamidematerial selected from the following: nylon 6; nylon 6,6; nylon 11; ornylon 12; or other nylon alloy. It should be noted that the selection ofa particular polyamide material should be based upon the physicalrequirements of the particular hose assembly application. For example,nylon 6 and nylon 6,6 offer higher heat resistant properties than nylon11 or nylon 12, whereas nylon 11 and nylon 12 offer better chemicalresistant properties than nylon 6 or nylon 6,6. Thus, the ultimateselection of a polyamide material should be based upon requirements of aparticular hose assembly application.

In addition to those polyamide materials previously mentioned, othernylon materials such as: nylon 6,12; nylon 6,9; nylon 4; nylon 4,2;nylon 4,6; nylon 7; and nylon 8 may also be used. Ring containingpolyamides including aliphatic-aromatic polyamides e.g. nylon 6,T andnylon 6,I may also be used. Finally, the outer layer 14 may also be madeof various polyamide blends. Again, it is noted that the selection ofparticular polyamide material is dependent upon the specific physicalrequirements of a particular hose assembly.

The outer layer 14 can be made of an expanded polyamide material, as isshown in FIGS. 1, 2, and 3. Alternatively, the outer layer 14 caninclude an unexpanded polyamide material. Although expanded andunexpanded polyamide outer layers 14 both offer the hose assembly 10increased tube and tensile strength, the expanded polyamide ispreferred. The expanded polyamide material offers the hose assembly 10substantially the same degree of strength as the unexpanded materialwhile significantly reducing the weight of the hose assembly 10. Thatis, the expanded polyamide material is significantly lighter in weightthan the unexpanded polyamide material due to the presence of voidspaces therein formed during the expansion process. The expansionprocess, commonly known in the art as “foaming”, generally takes placewhile extruding the outer layer 14.

Such foaming processes generally require blowing agents such as “CELOGENHT 550™”, or exothermic blowing agent sold by Uniroyal Chemicals or“ACTIVEX 537™”, or other endothermic blowing agent sold by B.I.Chemicals. The blowing agent is generally intermixed with a polyamidematerial during the extrusion of the outer layer 14 and causes expansionof the polyamide by producing gas, thereby forming void spaces withinthe outer layer 14.

The undulations or corrugations 42 on the outer layer 14, provideadditional bend radius to the hose assembly 10. There are two specifictypes of undulations or corrugations that may be present on the outerlayer 14, there types are spiral (FIG. 2) or circular (FIG. 3)undulation. Further, the entire hose assembly 10 or portions thereof maybe corrugated. This allows the manufacturer to undulate or corrugateonly those portions which will be bent thereby only providing thisadditional support where necessary.

There are a number of methods for fabricating the hose assembly 10, oneparticular well known method involves a two part extrusion processtypically known as “cross-head” extrusion. The typical “cross-head”extrusion method involves first extruding an inner layer, such as thefluoropolymer inner layer 12, then extruding an outer layer thereover,such as the polyamide or outer layer 14. This method of fabrication isparticularly effective when utilizing an inner layer 12 comprisingpolytetrafluoroethylene. Additionally, when utilizing thermoplasticfluoropolymer materials, co-extrusion methods of fabricating may beapplicable. As commonly known in the art, co-extrusion methods involvingutilizing two extruders at once thereby forming both inner and outerlayers simultaneously.

After the hose assembly has been formed, the hose is sent through amolding machine. The molding machine is made up of pairs of presses 44which form the corrugation or undulation on the outer surface of theouter layer 14. The mold presses 44 are configured to form undulationson the opposite sides of the hose 10 thus creating the undulations aboutthe entire outer surface of the outer layer 14. This allows themanufacturer to either undulate or corrugate the entire hose 10 or onlyportions thereof. Additionally, the presses 44 are slidably attached tothe molding machine thus allowing the presses 44 to be moved thusenabling the manufacturer to determine what part of the tubing will beundulated. Also, there are two specific types of undulation that may bepresent on the outer layer 14, these types are spiral (FIG. 2) orcircular (FIG. 3) undulation. The type of undulations 42 depend upon theconfiguration of the mold presses 44 or pressure forming the outsidewith internal mandrels or cross head extrusion with an internal mandrelwith pressure forming dies outside. Due to the chemical inertness andgeneral lubricious nature of fluoropolymer materials, relative movementbetween the inner 12 and outer 14 layers is often encountered. In hoseapplications which require immobility between adjacent layers, thepresent hose assembly 10 may be modified to eliminate such relativemovement between the inner 12 and outer 14 layers.

One embodiment for eliminating relative movement between the inner 12and outer 14 layers involves etching an outer surface 20 of the innerlayer 12 prior to disposing the outer layer 14 thereabouts, as shown onFIG. 4. Etching techniques are well known in the art and examples ofcommon etching techniques include acid treatment, plasma treatment, andmechanical scuffing and adhesive. Subsequent to etching, the outersurface 20 of the inner layer 12 maintains an irregular configuration 22as shown in FIG. 4. Essentially, the irregular configuration 22 includesof rough surface having a plurality of cavities and protuberancestherein.

Subsequent to etching the outer surface 20 of the inner layer 12, theouter layer 14 is extruded thereover. During this extrusion, an innersurface 24 of the outer layer 14 shapes into mating engagement with theirregular configuration 22 of the outer surface 20 of the inner layer12, thereby resulting in a mechanical and/or chemical bond therebetween.This mechanical bond prohibits relative movement (rotational orlongitudinal) between the inner 12 and outer 14 layers.

An alternative embodiment for eliminating relative movement between theinner 12 and outer 14 layer is shown on FIG. 1. The alternativeembodiment includes disposing of at least one braided layer between theinner 12 and outer 14 layers. More specifically, the alternativeembodiment includes a braided or woven layer 26 disposed in aninter-weaving fashion, or wrapped tightly about the outer surface 20 ofthe inner layer 12. Preferably, the material used for the braided layer26 is a glass fiber. Glass fibers are preferred due to relative low costand superior heat resistant properties.

The braided or woven fibers can be tightly wound or they may be looselywound about the inner layer 12, having wide gaps between adjacentfibers. Subsequent to position of the braided layer 26 about the innerlayer 12, the outer layer is extruded thereover. During this extrusion,the inner surface 24 of the outer layer 14 shapes into mating engagementwith the irregular configuration 31 of the intermediate coating 28thereby resulting in mechanical and/or the chemical bond therebetween,the chemical bond only occurring when there are gaps between the braid.This mechanical bond prohibits relative movement (rotational andlongitudinal) between a braided layer 26/intermediate coating 28 andouter layer 14.

Additionally, as fluid flows to the inner layer 12, electrical chargestend to build throughout the length of inner layer 12. In order toprevent these electrical charges from accumulating, the inner layer 12preferably includes an integral, longitudinal conductive strip 16co-extensive with the length of the inner layer 12 for conductingelectrical charge along the length of the inner layer 12. Preferably theinner integral conductive strip 16 includes of conductive strip 30 ofcarbon black, as shown in FIG. 1. Alternatively, the integral conductivestrip 16 may include an inner layer 32 of carbon black positionedadjacent an inner surface 33 of the inner layer 12 as shown in FIGS. 2and 3. Alternatively, the integral conductive strip 16 may beinterspersed throughout the inner layer 12 by intermixing carbon blackthroughout the fluoropolymer material while the inner layer 12 isextruded. The braided layer 26, intermediate coating 28, and outer layer14 are all preferably electrically nonconductive. This is important inthat electrical charges applied to the exterior of the hose assembly 10will not be conducted along its length nor to the fluid passingtherethrough. It will be appreciative that the integral conductive stripmay is include conductive material other than carbon black.

The assembly 10 further includes a coupling mechanism 18 as shown inFIG. 4. The coupling mechanism 18 is adapted to engage the ends of thehose assembly 10 for interconnecting the hose assembly 10 to a flow offluid, e.g. fluid flow 2 and from a fuel tank 35. More particularly, thecoupling mechanism 18 includes a coupler 18 or joint having an insertportion 34 for inserting into and engaging the inner surface 33 (FIGS. 1and 2) of the inner layer 12. The insert portion 34 may have a pluralityof barbs 36 for engaging the inner surface 33 (FIGS. 1 and 2) of theinner layer 12, as thus viewed in FIG. 4. The coupling mechanism 18 mayalso include an engaging portion extending longitudinally from theinsert portion 34 for engaging a fitting. The engaging portion mayinclude a male threaded member or a female threaded member. The engagingportion may include any configuration that will cooperate with themember to which it is to be connected with. For example, the engagingportion can include a socket to receive a mating ball joint.Alternatively, in place of the engaging portion, the coupling mechanism18 can provide an additional insert portion 34 for inserting into theinterior surface of the inner layer 12 of another hose assembly 10 asshown in FIG. 4. Thus, the coupling mechanism 18 can operate as a jointbetween independent hose assemblies 10 thereby interconnecting them toallow fluid flow therebetween. The coupling mechanism 18 is preferablymade from organic polymeric material and mechanically connected to thehose assembly 10, as shown in FIG. 4. Alternatively, the couplingmechanism 18 can be molded to the hose assembly.

A typical application of the present hose assembly 10 is shown in FIG.4. FIG. 4 discloses an engine 37, fuel tank 33, and three distinct usesof the present hose assembly 10. A fuel line for conveying fuel betweena fuel rail 40 and the fuel tank 35 is shown at 38. Coupling mechanism18 as previously described, interconnects the fuel line 38 with the fuelrail 40 fuel tank 35. The fuel rail 40 provides a flow of fuel to aplurality of fuel jumpers 42. Although not shown in FIG. 4, it will beappreciated to those skilled in the art that a gas manifold and throttlebody can be substituted for the fuel tail 43. The fuel jumpers 42 areinterconnected to the fuel rail 40 by ways of the coupling mechanism 18,as shown in FIG. 4, or alternatively, it may be molded directly to thefuel rail 40. Fuel injections for injecting fuel into individual fuelcylinders are shown on phantom at 44. The fuel injectors 44 may includemale supports 46 for inserting and engaging the inner surface of thefuel jumper 42, in a similar manner as the insert portion 34 of thecoupling mechanism 18 engages the inner surface 33 of the inner layer12.

Although the diameters of the fuel line 38, fuel rail 40, and fueljumper 42 may differ, all are made from the hose assembly 10 asdescribed above. That is, each includes a fluoropolymer inner layer 12and a polyamide outer layer 14 having undulations 42. Due to possiblevariances in diameter along each hose is assembly 10, i.e., fuel line38, fuel rail 40, fuel jumper 42 and fuel filler pipes, it will beunderstood that the insert portion 34 of the coupling mechanism 18 usedto interconnect each hose assembly 10 must vary correspondingly toaccommodate each specific hose assembly 10 diameter.

Although the present hose assembly has been described for conveyingfuels, it will be readily appreciated that the present hose assembly 10may be used for conveying a variety of fluids, e.g., cooling fluids,lubricating fluids, etc.

Throughout this application, various publications, including UnitedStates patents, are referenced by citation or number. All citations forthese publications are listed below. The disclosure of thesepublications and patents in their entireties are hereby incorporated byreference into the application in order to more fully describe the stateof the art to which this invention pertains.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description, rather than of limitation.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than is specifically described.

1. A hose assembly comprising: an inner fluoropolymer layer having anentirely smooth non-corrugated inner surface; an outer polyamide layerextruded about said inner layer, said outer layer having a corrugatedouter surface, said hose assembly being used in a fuel line; and atleast one braided layer disposed on said inner layer.
 2. The assemblyaccording to claim 1, further characterized by said outer polyamidelayer having a corrugated outer surface alternating with a smooth outersurface.
 3. The assembly according to claim 1, further characterized bysaid inner fluoropolymer layer being melt extrudable.
 4. An assemblyaccording to claim 1, further characterized by said inner fluoropolymerlayer being chemically resistant to fuels and fuel additives.
 5. Anassembly according to claim 1, further characterized by said braidedlayer comprising glass fibers.
 6. An assembly according to claim 1,further characterized by said polyamide material of said outer layerincluding a material selected from the group consisting essentially of:nylon alloy, nylon 6; nylon 6,6; nylon 11; and nylon
 12. 7. An assemblyaccording to claim 6, further characterized by said fluoropolymermaterial of said inner layer including a material selected from thegroup consisting essentially of: polytetrafluoroethylene; perfluorinatedethylene-propylene; perfluoroalkoxy fluorocarbon resin; andpolyfluoroethylene, THV, modified fluoropolymer.
 8. An assembly as setforth in claim 1, further characterized by said outer polyamide layerbeing expanded or not expanded.
 9. An assembly as set forth claim 1,further characterized by said inner fluoropolymer layer being expandedor unexpanded.
 10. An assembly as set forth in claim 1, furthercharacterized by said outer polyamide layer having spiral undulations onsaid outer surface.
 11. An assembly as set forth in claim 1, furthercharacterized by said outer polyamide layer having circular undulationson said outer surface.